The correspondence includes an interesting letter from M. Humboldt, dated Lima, Nov. 25. 1802, containing an account of his travels in South America; from which we shall extract a short description of the province of Quito.

‘This province, which is situated on the most elevated plain in the world, and which has been rent by the grand catastrophe of Feb. 4. 1797, has opened a most extensive field of physical observation.

Here are volcanoes so enormous as to cause the flame often to ascend 3000 feet; which nevertheless do not produce one drop of running lava, but which vomit forth water, sulphuric hydrogene gas, mud, and carbonated argil.

Since the year 1797, the whole of this part of the world has been in agitation: we experience at every instant frightful shocks: and the subterraneous noise in the plains of Rio Bamba resembles that of a mountain falling to pieces under our feet.

Atmospheric air, and moistened earth, (for all these volcanoes are in a decomposed porphyry,) appear to be the grand agents in these combustions and subterraneous fermentations.’

‘It was till now believed at Quito that the rarefaction of the air, at the elevation of 2,470 toises, was the greatest which men could endure.

In the month of March 1802, we passed some days on the vast plains surrounding the volcano of Antisana, at 2,107 toises elevation, where the oxen, when we chased them, vomited blood.

On the 16th of March, we discovered a path in the snow on which we mounted to the height of 2,773 toises.

The air contained 0,008 of carbonic acid, 0,218 of oxygene, and 0,744 of azote.

It was not cold, but the blood gushed out from our lips and eyes.

In my expedition of June 23, 1802, to Chimboraço, we proved that, with patience, man might sustain a very great rarefaction of the air.

We carried our instruments on Chimboraço as high as 3,031 toises, and saw the mercury descend in the barometer to 13 inches and 11,2 lines.’

By two operations, M. Humboldt found the top of Chimboraço to be 3,267 toises above the level of the sea.

It has often been asserted, he adds, that this mountain is of granite, but he found not a single atom.

It is a bed of porphyry, 1,900 toises thick, intermixed with vitreous feld-spath, &o.

The letter closes with a reference to the botanical treasures which the writer had discovered: but here we must not dilate; though we cannot help congratulating our readers that, to the bread-fruit-tree and the butter-tree, M. Humboldt has added the milk-tree, or, as the Indians call it, the vegetable cow.